This is one of the best features of hikashop.
In the backend when you are in the products area, there is an "Export" button up in the upper right toolbar area.
It exports a CSV file of your products that we like to open with Excel for easily changing things like Pricing, Products Details, etc. and then use the "Import" feature that is in the "Products" tab of the hikashop menu.
The import feature will create any new products that you have added to your CSV file and Update any existing products. It goes off of the "product_code" field to determine if the product is new or already existing.
Import/Export is by far one of the most powerful features of hikashop we use time and time again.